Phenolic and aromatic amine polymer resins constitute a very important and useful class of chemical compounds. They have a number of uses, e.g., as coatings and laminates that provide a number of functional advantages. Besides possessing good thermal properties, these polymers can be doped to make them electrically conductive, making them a key component of integrated circuit (IC) chips.
At present, these polymers are prepared by chemical synthesis, e.g., as from phenol and formaldehyde. The polymers's linearity/network structure (and, by extension, their functional properties) varies depending on the monomer and type of reaction conditions used. However, the use of certain constituent chemicals, such as formaldehyde, is being restricted in the chemical industry because of their toxicity. Accordingly, the enzyme-mediated synthesis of polyphenols and polyaromatic amines offers a viable alternative to the currently used chemical synthesis of such commercial phenolic resins.
Peroxidase-catalyzed free radical polymerization of phenol, aromatic amines, and their derivatives is well known. Horseradish peroxidase (HRP) is the most widely used biocatalyst in the polymerization of phenol, aniline, or their derivatives. HRP has been shown to be active in a number of organic solvents or solvent mixtures and the reaction is typically initiated by the addition of hydrogen peroxide as an oxidant.
Dordick et al., Vol. #30 1987 Biotechnol. Bioeng. 31-36, used HRP in a dioxane/water system to prepare a number of polymers and copolymers from various phenolic monomers. Akkara et al., 29 J. Poylm. Sci. A 1561 (1991), prepared polymers and copolymers of various phenols and aromatic amines using these same reactions and carried out detailed characterization of the polymer products. p-Alkylphenols were also polymerized at oil-water (reversed micelles) and air-water (Langmuir-Blodgett trough) interfaces. Because of their amphiphilic nature, the alkylphenols are positioned at the interface, and in the presence of HRP and hydrogen peroxide the monomers are oxidatively coupled to form polymers. The poly(p-alkylphenols) prepared in reversed micelles were shown to exhibit relatively more uniform molecular weight distribution than those prepared in bulk organic solvents.
However, earlier attempts to control the polymer molecular weight and molecular weight distribution by varying the time of reaction or hydrogen peroxide concentration were unsuccessful in both reversed micelles and bulk solvents. Initial hydrogen peroxide concentration was found to be stoichiometrically proportional to the monomer conversion, a hallmark of stepwise polymerization and a phenomenon observed previously, and there was no effect on the polymer molecular weight and polydispersity.
The polymers can be modified by adding functional groups to the polymeric backbone, significantly enhancing the utility of these polymers. "Functionalization" enables the polymers to be used to treat fabrics, to form selectively permeable membranes, and to improve the performance of IC chips, among other applications.
Palmitoyl chloride may be added to the polymer to make the polymer easily processable, e.g., as coatings, films, or finishes. Cinnamoyl chloride may be added to create controlled pore size membranes (e.g., "molecular sieves") or to enhance the polymers's ability to absorb UV radiation (e.g., for sunglasses), thereby enabling their use as anti-reflective coatings in photoresists. In their latter use, the modified polymers are applied to a silicon substrate as an undercoating (under non-functionalized polyphenols or polyaromatic amines that are then applied as a spin coating) in an IC chip to control the precision of UV etching, by inhibiting UV scattering, of circuitry into the spin-coated polymer layer. In addition, these cinnamoyl chloride-modified polymers are very thermostable, which allows their use in a variety of applications where heat is ordinarily a problem. In contrast, photosensitive functional groups may be added to enhance the utility of the polymers in other applications.
The polymers also may be modified to create active matrices and systems allowing the controlled-release of materials, such as drugs, insecticides, and fertilizers. If biotin groups are added to the polymer chain, the polymer can be used as chromatography packing, which may be used to separate and purify proteins.
Despite the study of how the functionality of the polymers varies depending upon whether, and with what, the molecules are modified, it has not been shown that the molecular weight and the molecular weight distribution (i.e., the "polydispersity") of polyphenols and polyaromatic amines also can significantly influence the functional properties of the polymers.
Accordingly, it is an object of this invention to overcome the above illustrated inadequacies and problems of extant polyphenols and polyaromatic amines by providing an improved method of their manufacture suitable for use in applications that would benefit from uniform polymer size.
It is another object of this invention to provide a method of producing polyphenols and polyaromatic amines wherein it is possible to control the molecular weight distribution of the polymer molecules.
Yet another object of the present invention is to provide a method of producing polyphenols and polyaromatic amines wherein the molecular weight distribution of the polymer molecules is between 600 and 3,600.
It is a further object of the present invention to provide a method of producing polyphenols and polyaromatic amines wherein the molecular weight distribution of the polymer molecules is between 1,400 and 25,000.
A still further object is to provide a method of producing polyphenols and polyaromatic amines wherein it is possible to control the polydispersity of the polymer molecules.
It is another object of this invention to provide a method of producing polyphenols and polyaromatic amines wherein the polydispersity of the polymer molecules ranges from 1.02 to greater than 2.
It is yet another object of the present invention to provide a method to modify the polymer prepared by adding functional groups to the polymer using palmitoyl chloride, cinnamoyl chloride, and biotin compounds.